Before he was Dr. Strangeglove, Dick Stuart was already the stuff of legends with his 66-homer season for the Lincoln Chiefs of the Western League in 1956. There are numerous photos of that season around, but this would seem to be an original version of the image used on his Mutual Savings postcard from that year.
FYI: you won't find it in Baseball Reference, which still has yet to bestow us with many minor league RBI totals, but Stuart drove in 158 runs that season. And showing that he was a hitter ahead of his time, he also struck out 171 times in 141 games.